Column spring snap switch



March 21,1950 D. L. CLARK EIAL 2,501,497

COLUIN SPRING SNAP SWITCH Filed Oct. 7 19 47 Inventor-s: David L. Clavk, James F. Young,

by I I Their Attorney.

Patented Mar. 21, 1950 COLUMN'SPRING SNAP swrrcn David L. Clark and James F. Young, Bridgeport. Conn., assignors to General Electric Company, a corporation of New York Application October 7, 1947, Serial No. 778,384

9 Claims. (Cl. 200-67) The present invention relates to column spring snap switches and has for its object to provide an improved construction and arrangement in a switch of this type.

For a consideration of what we believe to be novel and our invention, attention is directed to the following specification and to the claims appended thereto.

In the drawing, Fig. 1 is a sectional view of a column spring snap switch embodying our invention; Figs. 2 and 3 are perspective views of the switch movement, and Fig. 4 is a detail view of a modification.

Referring to the drawing, I indicates a column spring having adjacent to one end a contact button 2. Our invention has to do particularly with the switch movement, i. e., the mounting for the column spring. According to our invention, we mount the column spring in a stiff metal frame 3, the spring being fixed to the frame at one end by a suitable means, such as by welding, as is indicated at 4 in Fig. 2 and being free at its other end, as is indicated at 5. At end 5, the end of spring I engages the end of the frame to hold the spring in its wave formation.

Frame 3 comprises preferably a top wall or bridge 6 and strengthening or reinforcing side walls I which serve to give rigidity to the frame. In top wall 6 is an opening 8 in line with contact button 2 and an opening 9 through which an actuator for the spring may engage the spring. Frame 3 may be formed from suitable strip stock metal in one piece. At its ends, it is reversely bent on itself to provide end walls I and II at one end of the frame and end walls I2 and I3 at the other end, between which the ends of the column spring are positioned. End walls In and I2 are notched at their side edges to receive lanced-in projections I4 and I which serve to center spring I laterally with respect to side walls I. Formed integral with end wall 10 is a terminal I6 for an electrical connection to spring I.

The inner edge of wall I0 is accurately positioned with respect to the inner edge of wall II to provide opposed shoulders I! and similarly, the inner end edge of wall I2 is accurately positioned with respect to wall I3 to provide opposed shoulders I8. These shoulders are opposite each other and define exactly the length of spring I and provide opposed accurately spaced edges over which it bends. Wall I2 may be bowed slightly (it being so shown in somewhat exaggerated form) to sharply define the edges at this end of the frame. At its left-hand end, the frame may be provided with a slot is through which spring I may be initially assembled in the frame. In assembling the structure, the spring I may be slipped into the frame, from the center, endwise through slot I9 until the contact button strikes edges II, then reversed in direction and slipped between edges I 8 until it engages the end 5 of the frame. It may be then placed in a suitable fixture which holds the spring against the end 5 of the frame and at the same time gives the spring the desired wave formation. While so held, the end of the spring is fastened, preferably by welding, between the walls In and I I. This makes for easy accurate assembly of th spring in the frame and gives it the exact wave formation desired. From a manufacturing point of view, it is especially advantageous in that it enables switch movements to be rapidly and accurately assembled with relatively unskilled labor while at the same time assuring exact constructions in each instance. It eliminates dependence on manual adjustment for end compression on the column spring since the end compression is set in the welding fixture.

The switch movement is a unit in itself and may be utilized in any suitable form of easing. In the present instance, it is shown as being assembled in a casing comprising a base 20 and a cover 2|, the cover being attached to the base by screws 22. As shown, base 20 is provided with contacts 23 and 24 with which contact 2 on the column spring engages. This provides for control of two circuits. If control for a single circuit is desired, one of the contacts 23 or 24 may be omitted. At 25 and 26 are lugs to which circuit wires may be connected. The column spring is shown as actuated by a pin 21 which projects through an opening in base I and is carried by a pivoted arm 28. In the present instance, the column spring is shown as being biased to a position wherein contact 2 is in engagement with contact 23 by a spring 29. It will be understood that this is only byway of example, and that if desired, the spring may be biased in the opposite direction or it may be positively actuated in each direction.

Since one end of the spring is not connected to the frame, it may slide axially with respect to the bridge with overtravel of the operating member 21. In switch applications where the overtravel is small, we may, if desired, weld both ends of the spring to the frame. This is illustrated in Fig. 4 where the end of the spring which is free in Figs. 1 to 3 is shown as being welded to the frame as indicated at 30.

Our construction is especially advantageous in that the rigid frame in which the column spring is held serves to maintain accurately the active length and wave form of the column spring. This is important since changes in the wave form from that which has been determined to give effective snap action effect adversely the operation of the switch. In this connection it is desirable to employ a metal for the frame having about the same temperature coefficient of expansion as the column spring. Since the column spring is held entirely by the metal frame, variations in the dimensions of the casing in which the switch movement is mounted do not affect the operation of the switch. This is important. because in general, molded plastic casings in which switches are mounted have a tendency to change dimensions due for example to humidity and aging.

Our improved construction, has the advantage also that since the switch movement is in substance a unitary preset structure, should replacement be needed it is necessary merely to remove the one switch movement and replace it with a new one; and in doing this, no adjustments of any kind are required.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. In a column spring snap switch, a casing, a rigid metal frame supported in the casing having reversely bent ends, a column spring which extends longitudinally of the metal frame, has one end fixed within the reversely bent end at one end of the frame and the other end slidable within the other reversely bent end at the other end of the frame and abutting a wall of the frame at such end to hold the column spring in wave form, contact means carried by the casing and column spring, and an actuator for effecting movement of the column spring.

2. For use in a column spring snap switch, a switch movement comprising a rigid metal frame having reversely bent ends to provide elongated pockets and a column spring which extends longitudinally of the metal frame, has one end fixed within the frame pocket at one end of the frame and the other end slidable within the frame pocket at the other end of the frame and abutting a wall of the frame at such end to hold the column spring in wave form.

3. For use in an electric switch, a switch movement comprising a rigid metal frame having a top wall and reinforcing side walls, the ends of the top wall being reversely bent and a column spring having one end fixed within the reversely bent end at one end of the frame and the other end slidable within the reversely bent end at the other end of the frame and abutting a wall of the frame at such end to hold the column spring in wave form, one fold of each of said reversely bent ends being provided with projections en" gageable with the side edges; of said spring to maintain the position of the spring relative to the sides of the frame. 7

4. For use in an electric switch, a switch movement comprising a rigid metal frame having a top wall and reinforcing side walls, the ends of the top wall being reversely bent and a column spring having one endfixed within the reversely bent end at one end of the frame and the other end slidable within the reversely bent end at the other end of the frame and abutting a wall of the frame at such end to hold the column spring in wave form, the bend at the one end of the frame being provided with a slot through 4 which the column spring may be inserted into the frame.

5. In a column spring snap switch, a casing, a rigid metal frame supported in the casing hav- 5 ing reversely bent ends to provide pockets having mutually opposed mouths, and a column spring which extends longitudinally of the metal frame, has one end fixed within said pocket at one end of the frame and the other end slidable within said pocket at the other end of the frame and abutting a wall of the frame at such end to hold the column spring in wave form, the ends of said reversely bent ends at the mouths of the respective pockets forming shoulders which define the effective length of the column spring and over which the column spring ends flex.

6. For use in an electric switch, a switch movement comprising a rigid metal frame having a top wall and reinforcing side walls, the

ends of said top wall being reversely bent to form mutually aligned elongated pockets having sharply defined, opposed shoulders at the entrance of each pocket, and a column spring positioned between said side walls and extending into said pockets for support by the respective upper and lower walls thereof and at least one end of said spring being fixed thereto; the said opposed shoulders providing accurately spaced fulcrum points for the flexure of said spring, and the relaxed length of said spring being greater than the spacing between said fulcrum points, whereby when confined within said pockets the spring will assume a wave form.

7. For use in an electric switch, a switch 3;; movement comprising an elongated, rigid, metal frame having end portions reversely bent to form mutually aligned pockets, a column spring having one end fixed within the pocket at one end of the frame and the other end slidable within the other pocket, wall means in said other pocket against which said spring abuts to establish a normal wave form of said spring, and projections fixed relative to said frame at said last-named pocket and engaging with the side edges of the spring to maintain the position of the spring relative to the sides of the frame.

8. A column spring snap switch comprising a rigid frame member of channel formation having end wall portions reversely bent to form mutually aligned elongated pockets, each said pocket having transversely extending shoulder means at its entrance to define fulcrum points; a column spring member positioned within said frame member and secured within said pockets for continuous engagement with said fulcrum points,

said spring .member having a length such that when confined within said pockets it will assume a wave form of fixed length represented by the spacing of the said fulcrum-points; means for flexing said spring member from its normally assumed wave form; and switch contact means operated from one to another circuit condition upon flexure of said spring member.

9. A column spring snap switch comprising a rigid frame member of channel formation having end wall portions reversely bent to form mutually aligned elongated pockets, each said pocket having transversely extending shoulder means at its entrance to define fulcrums; a column spring member positioned within said frame member and fixedly secured relative thereto within each said pocket in continuous engagement with said fulcrums, said spring member having a length such that when fixed within said pockets it will assume a wave form of fixed length represented by the spacing of said fulcrum points, means for flexing said spring member from its normally assumed wave form, and switch a contact means operated from one to another circuit condition upon flexure of said spring' member. 7

DAVID L. CLARK.

JAMES F. YOUNG.

REFERENCES CITED The following references are of record in the file of this patent;

Number UNITED STATES PATENTS Name Date Eskin Oct. 16, 1934 Rich Mar. 16, 1937 Bokeeno Apr. 5, 1938 Schmidinger Oct. 18, 1938 Dehlendorf Feb. 11, 1941 Heikes Apr. 17, 1945 Ulanet Feb. 5, 1946 Aitken Dec. 24, 1946 

